HAVANA (AP) — A Norwegian-owned platform arrived in waters off Cuba’s north-central coast for exploratory drilling by the Russian oil company Zarubezhneft, authorities said Saturday, renewing the island’s search for petroleum after three failed wells this year.

Drilling is to begin “in the coming days” and take six months, according to a notice published by the Communist Party newspaper Granma. The depth of the project was given as 21,300 feet (6,500 meters).

State-run oil company Cubapetroleo said in the announcement that the Songa Mercur rig, owned by Songa Offshore of Norway, was inspected to make sure it contains less than 10 percent U.S.-made parts. That allows the companies involved in the drilling to avoid sanctions under the 50-year-old U.S. embargo against Cuba.

The exploration block in question, near the gleaming beaches of a major tourist resort, is considered less promising than offshore areas to the west where earlier this year a superdeep-water platform drilled three wells deemed commercially nonviable.

The Scarabeo-9, a huge semisubmersible rig owned by Italy’s Saipem, left Cuban waters last month after sinking the three dud wells, and analysts said it could be years before drilling resumed in those deep-water blocks.

Geologic surveys say 5 billion to 9 billion barrels of oil may lie off Cuba’s coast. Island authorities hope there may be even more and have been banking on a big strike.

An injection of petrodollars could boost Cuba’s struggling economy, bankroll President Raul Castro’s economic reforms and ease the island’s energy dependence on Venezuela, which has sent billions of dollars’ worth of oil on preferential terms.

“The new well has the objective of determining the potential of petroleum and natural gas in this sector of our country,” the notice in Granma read. “Its results should contribute to the knowledge of the area of the perforation, as well as all of north-central Cuba.”

Cuba’s oil exploration in the Gulf of Mexico has prompted protest from Cuban exiles in the United States and alarmed some who fear a spill could befoul American shores from Florida to the Carolinas.

The notice in Granma said the Songa Mercur rig also underwent safety inspection and is capable of drilling with minimum environmental risk.